Recent Advances on Computational Investigations of <i>N</i>‐Heterocyclic Carbene Catalyzed Cycloaddition/Annulation Reactions: Mechanism and Origin of Selectivities

Wang, Yang; Wei, Donghui; Zhang, Wenjing

doi:10.1002/cctc.201701119

Cited by 110 publications

(29 citation statements)

References 189 publications

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“…In light of the selectivities in the TS3‐isomers, the different reactivities of the double bonds and the different interactions between the Int2‐Ester and Z1 moieties could be another important reason that results in the selectivities. In this case, noncovalent interactions may play a dominant role as observed elsewhere in similar scenarios.…”

Section: Resultsmentioning

confidence: 99%

DFT mechanistic study on tandem sequential [4 + 2]/[3 + 2] addition reaction of cyclooctatetraene with functionalized acetylenes and nitrile imines

Opoku

Tia

Adei

2019

J of Physical Organic Chem

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The mechanistic pathways for the tandem sequential [4 + 2] / [3 + 2] and [3 + 2]/[4 + 2] cycloaddition reaction of functionalized‐acetylenes with cyclooctatetraene (COTE) and nitrile imines for the formation of the biologically‐active tricyclic cyclobutane‐condensed pyrazoline systems, and the subsequent cycloreversion/thermolysis of these adducts, have been studied using density functional theory (DFT) at the M06‐2X/6‐31G(d) and 6‐311G(d,p) levels with the aim of providing mechanistic rationale for the regioselectivities and stereoselectivities. Along the [4 + 2] / [3 + 2] addition sequence, it has been found that the initial 6π‐electrocyclic ring‐closure of the COTE is the rate‐determining step irrespective of the type of substituent on the parent acetylene or the nitrile imine. The mechanistic channels along the [4 + 2] / [3 + 2] addition sequence show that the addition of the dipole across the unsubstituted olefinic bond in the cyclohexadiene moiety in the endo fashion is the most favored, which is in agreement with experimentally observed selectivity. The results show that the thermolysis proceeds with relatively high activation barriers toward formation of the monocyclic pyrazolines among other products. The decomposition of the tandem adducts has been found to be controlled solely by kinetic factors. An exploration of a [3 + 2] / [4 + 2] addition sequence as a mechanistic possibility reveals that in contrast to the [4 + 2] / [3 + 2] addition sequence, the Diels‐Alder addition step is the rate‐determining. The [3 + 2] / [4 + 2] addition order is found as an approach with better selectivity as it leads to formation of only tandem adducts where the nitrile imines are attached to the substituted olefinic bond in the cyclohexadiene subunit. The results show that the monocyclic pyrazolines obtained from the thermolysis of the [4 + 2] / [3 + 2] tandem adducts could easily be obtained from a direct 1,3‐dipolar addition of the alkynes with the dipoles which has been found to proceed rapidly with low activation barriers. The results are rationalized with perturbation molecular orbital theory.

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Section: Resultsmentioning

confidence: 99%

DFT mechanistic study on tandem sequential [4 + 2]/[3 + 2] addition reaction of cyclooctatetraene with functionalized acetylenes and nitrile imines

Opoku

Tia

Adei

2019

J of Physical Organic Chem

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“…The DFT calculations were performed with the Gaussian 09 program. [20] Noteworthy,C AM-B3LYP [21] functional performs well for charge transfer excitations and promises the similar energy calculation accuracy with B3LYP in solvent, [21,22] and M06-2X [23] functional with the higher basis set to calculate single-point energy can afford more reliable results in the organocatalyst-catalyzed reactions, [6,17,23] so we performed all the calculations at the M06-2X/6-311 ++G(d,p)/IEF-PCM THF [24] //CAM-B3LYP/6-31G(d)/IEF-PCM THF level. Optimization of all of the reactants, intermediates, transition states, and products was performed at the CAM-B3LYP/6-31G(d)/IEF-PCM THF level.…”

Section: Computationaldetailsmentioning

confidence: 99%

“…[2] In addition, organocatalysts enlarge the synthesis domain and simultaneously have similar activities to enzymes. [3] In particular, Lewis base organocatalysts, including organophosphines, [4] amines, [5] and nucleophilic carbenes, [6] are widely used as nucleophiles to attack the carbonyl, [7] olefin, [4] or alkyne [8] carbon atoms to initiate stereoselective reactions, which has become and continues to be one of the hottest topics in asymmetricsynthesis.…”

Section: Introductionmentioning

confidence: 99%

Insight into Isothiourea‐Catalyzed Enantioselective Addition of Saturated Esters to Iminium Ions

Liu

et al. 2019

Chemistry An Asian Journal

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The possible mechanisms and origin of the selectivities of isothiourea‐catalyzed addition of saturated esters to iminium ions have been investigated by density functional theory. The favorable reaction pathway includes three stages: formation of an ammonium enolate intermediate, enantioselective addition of the ammonium enolate intermediate to the iminium ion, and dissociation of the catalyst to form the product. The enantioselective addition process is the stereoselectivity‐determining step, while the chemoselectivity‐determining step is included in the formation of the final product. The calculated energy barriers show that the chemoselectivity is thermodynamically controlled, and it depends on the polarities of the products and the nucleophilicities of the N atoms of the enamine reactant moieties of the intermediates. The origin of the stereoselectivity was investigated by non‐covalent interaction analysis of the key transition states. Hydrogen bonding interactions were identified as the determining factor for controlling the stereoselectivity. The obtained insight will be valuable for rational design of novel Lewis base organocatalyst‐promoted enantioselective addition reactions with special chemoselectivities.

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“…Gaussian09 was employed for all the calculations. DFT is the most powerful method for understanding the compound structures and reaction mechanism . All the geometries including reactants, intermediates, transition states, and products were obtained at ωB97XD/def2‐SVP theory level .…”

Section: Computationsmentioning

confidence: 99%

Me₃SiBr/InCl₃ catalyzed allylation of alcohols: Identifying the combined Lewis structure and investigating the reaction mechanism

Liu

Sang

Chen

et al. 2018

J of Physical Organic Chem

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The combined Lewis acid Me3SiBr/InCl3 shows unique performance in multireactions. The topology and catalytic properties of Me3SiBr/InCl3 were investigated by DFT method for clarifying the nature of chemical bonds and interactions. Quantum theory of atoms in molecules (QTAIM) analysis showed that the interaction between Me3Si‐halide and In‐trihalide mainly belongs to the closed‐shell interaction. Natural bond order of Br─In is 0.610 in INT_0 while natural bond order of Cl─In in INT_1 is only 0.081 at SMD‐ωB97XD/def2‐SVP level. The coupling reaction mechanism of alcohol and allyltrimethylsilane catalyzed by the complex of Me3SiBr/InCl3 was investigated with DFT method. The combined Lewis acid activates the hydroxyl group by strong coordination to silicone center, which leads to the generation of carbocation. Me3Si+ moiety from the combined Lewis acid is consumed and converts into the side product Me3SiOSiMe3. Furthermore, the reactant allyltrimethylsilane is introduced into the system to bring out the final product, and the complex Me3SiBr/InCl3 is reproduced at the same time. The combined Lewis acid Me3SiBr/InCl3 not only works as the catalyst for the reaction but also involves in the generation of side product.

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Recent Advances on Computational Investigations of N‐Heterocyclic Carbene Catalyzed Cycloaddition/Annulation Reactions: Mechanism and Origin of Selectivities

Cited by 110 publications

References 189 publications

DFT mechanistic study on tandem sequential [4 + 2]/[3 + 2] addition reaction of cyclooctatetraene with functionalized acetylenes and nitrile imines

DFT mechanistic study on tandem sequential [4 + 2]/[3 + 2] addition reaction of cyclooctatetraene with functionalized acetylenes and nitrile imines

Insight into Isothiourea‐Catalyzed Enantioselective Addition of Saturated Esters to Iminium Ions

Me₃SiBr/InCl₃ catalyzed allylation of alcohols: Identifying the combined Lewis structure and investigating the reaction mechanism

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Recent Advances on Computational Investigations of N‐Heterocyclic Carbene Catalyzed Cycloaddition/Annulation Reactions: Mechanism and Origin of Selectivities

Cited by 110 publications

References 189 publications

DFT mechanistic study on tandem sequential [4 + 2]/[3 + 2] addition reaction of cyclooctatetraene with functionalized acetylenes and nitrile imines

DFT mechanistic study on tandem sequential [4 + 2]/[3 + 2] addition reaction of cyclooctatetraene with functionalized acetylenes and nitrile imines

Insight into Isothiourea‐Catalyzed Enantioselective Addition of Saturated Esters to Iminium Ions

Me3SiBr/InCl3 catalyzed allylation of alcohols: Identifying the combined Lewis structure and investigating the reaction mechanism

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Product

Resources

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Me₃SiBr/InCl₃ catalyzed allylation of alcohols: Identifying the combined Lewis structure and investigating the reaction mechanism